K. G. BARRETT1, M. R. Bennink1, and K. D. Dolan2. (1) Dept. of Food Science & Human Nutrition, Michigan State Univ., 109 G. Malcolm Trout FSHN Bldg., East Lansing, MI 48824-1224, (2) Dept. of Food Science & Human Nutrition/Dept. of Agricultural Engineering, Michigan State Univ., 208 G. Malcolm Trout FSHN Bldg., East Lansing, MI 48824-1224
Large quantities of waste material are produced
during the harvesting and processing of Michigan fruits and vegetables. Cull blueberries, small onions and grape
pomace were selected because they contain high concentrations of phenolic
compounds (PC) and large quantities are available.
The objective of this study was to extract and
concentrate phytochemicals from cull blueberries, cull onions and grape pomace
on a pilot plant scale.
The
PC from each crop were extracted with 69%ethanol:30%water:1%hydrochloric
acid. After filtration, ethanol was
removed by continuous vacuum evaporation (temperature=26-49°C, vacuum=660-710
mm Hg) resulting in a condensed extract (phase I). The condensed extract was mixed with Optipore® (2:1,
v/v), a non-ionic resin to bind PC. PC
were eluted with ethanol and this extract was again condensed by continuous
vacuum evaporation (phase II). The
phase II concentrate was oven dried (phase III) at 50°C for 24-48hr. At each phase, samples were removed and
subjected to standard assays to determine total phenolic content and
antioxidant capacity (ORAC).
Table 1: Total phenolic content (TPC) and anitoxidant
capacity (ORAC) of cull blueberries, cull onions and grape pomace
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|
TPCa
|
ORAC Valuesb
|
|
|
Phase I
|
Phase II
|
Phase III
|
Phase I
|
Phase II
|
Phase III
|
|
Blueberryc
|
1.7
|
N/A
|
29.8
|
4.5
|
N/A
|
84.1
|
|
Blueberryd
|
100%
|
44%
|
8%
|
100%
|
39%
|
11%
|
|
Grape
Pomacec
|
1.3
|
N/A
|
63
|
1.7
|
N/A
|
173.6
|
|
Grape
Pomaced
|
100%
|
50%
|
18%
|
100%
|
43%
|
32%
|
|
Onionc
|
1.7
|
N/A
|
72.9
|
2.7
|
N/A
|
190.4
|
|
Oniond
|
100%
|
50%
|
39%
|
100%
|
43%
|
33%
|
a. Expressed as g (+)-catechin equivalents; b. Expressed as
mmol Trolox equivalents; c. TPC or ORAC value per kg of phase product; d. %Retained
The phase III products resulting
from aqueous-alcohol and Optipore® extraction were highly
concentrated in phenolic compounds, as well as, antioxidant capacity. This demonstrates that phenolic compounds
can be extracted and concentrated from the harvesting and processing wastes of
fruits and vegetables.
Session 33F, Nutraceuticals & Functional Foods: Antioxidants and phytochemical analysis
2:00 PM - 5:30 PM, Tuesday PM Room Hall N-1
2004 IFT Annual Meeting, July 12-16 - Las Vegas, NV
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